Stability of {gamma}{prime} phase in the stoichiometric Ni{sub 3}Al alloy under ion irradiation
- Hahn-Meitner-Inst., Berlin (Germany)
In the stoichiometric Ni{sub 3}Al alloy the ordered {gamma}{prime} phase is thermodynamically stable up to the melting temperature. Therefore, disordered Ni{sub 3}Al can only be obtained by non-equilibrium treatments such as by ball milling, or by various types of particle irradiation, e.g. by electrons, by protons, and by ions. Bourdeau and co-workers report weak intensities of the superlattice reflections in the Ni based alloy Nimonic PE16 under 300 keV Ni{sup +} irradiation up to fluences of 1 to 2 dpa. They are attributed to a non-zero state of order in the {gamma}{prime}-precipitates in this alloy. The aim of this work is to investigate the stability of the single phase ordered Ni{sub 3}Al under the same irradiation conditions as applied in the case of Nimonic PE16. It should answer the question, whether the superlattice reflections at 1 dpa can be also observed in the single phase Ni{sub 3}Al under irradiation. The authors used the fact that stronger intensities of the superlattice reflections and of the fundamental reflections are expected in the single phase Ni{sub 3}Al alloy than in Nimonic PE16 where the volume fraction of the {gamma}{prime} phase was only 6%. The observed fluence dependence of the decrease of the intensities of the superlattice reflections is in agreement with results found in Nimonic PE16 which were performed under the same irradiation conditions. But the disordering process strongly depends on the irradiation temperature. Interesting is the intensity decrease of the superlattice reflection intensities above 600 K after 10 dpa. The simple models of reordering (cascade reordering or/and vacancy diffusion-induced reordering) would both predict a stable highly ordered state for high influences. It is known that above 1 dpa the defect structure produced by the irradiation becomes an essential component of the alloy microstructure.
- OSTI ID:
- 69641
- Journal Information:
- Scripta Metallurgica et Materialia, Vol. 32, Issue 10; Other Information: PBD: 15 May 1995
- Country of Publication:
- United States
- Language:
- English
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